Meeting Abstract
Climate change threatens to increase rates of extinction by pushing organisms beyond their physiological limits, but we still lack an adequate understanding of the mechanisms that link organismal stress to population-level responses to climate change. Ecological predictions of climate change are primarily hindered by the complex nature of the climate-organism relationship and the lack of long-term ecological responses to climate. Here, we evaluated the potential for physiological stress associated with homeothermy to predict the recently discovered collapse of the desert bird community over the last century. We developed a physiologically-structured model to predict the stress associated with offloading excess heat via evaporative cooling as a mechanism driving decline. Our analysis revealed that the degree of evaporative cooling stress on hot days predicted the decline in occupancy over the last century. Large-bodied species experienced a greater increase in EHL demand than small-bodied species given the same change in air temperature over the last century. These predictions also provided a mechanistic understanding underlying intraspecific reductions of body mass in response to warm climates, a pattern described by Bergmann’s rule. Empirical reductions in body size from our species resulted in as much as 13% savings in water needed for homeothermy on an average day in the desert. Our predictions of future responses to climate change suggest a high probability for further population declines in desert environments due to stress associated offloading excess heat under future climate change.
